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Object: This study demonstrates that 3T SV-MRS data can be used with the currently available automatic brain tumour diagnostic classifiers which were trained on databases of 1.5T spectra. This will allow the existing large databases of 1.5T MRS data to be used for diagnostic classification of 3T spectra, and perhaps also the combination of 1.5T and 3T databases., Materials and Methods: Brain tumour classifiers trained with 154 1.5T spectra to discriminate among high grade malignant tumours and common grade II glial tumours were evaluated with a subsequently-acquired set of 155 1.5T and 37 3T spectra. A similarity study between spectra and main brain tumour metabolite ratios for both field strengths (1.5T and 3T) was also performed., Results: Our results showed that classifiers trained with 1.5T samples had similar accuracy for both test datasets (0.87 ± 0.03 for 1.5T and 0.88 ± 0.03 for 3.0T). Moreover, non-significant differences were observed with most metabolite ratios and spectral patterns., Conclusion: These results encourage the use of existing classifiers based on 1.5T datasets for diagnosis with 3T (1)H SV-MRS. The large 1.5T databases compiled throughout many years and the prediction models based on 1.5T acquisitions can therefore continue to be used with data from the new 3T instruments.

Object: Automatic accurate measurement techniques are needed to increase reproducibility in the quantification of cervical cord area (CCA) with magnetic resonance (MR) imaging in the assessment of central nervous system (CNS) atrophy in multiple sclerosis (MS) patients., Materials and Methods: Two segmentation methods were implemented: (1) spatial mean brightness level estimation (SMBLE), and (2) partial-volume modeling (PVM). These were evaluated with the inclusion of spinal cord inclination and/or partial-volume-effect corrections. An averaged manually segmented set was considered as reference. Thirty MR studies were used to compare the different methods. A set of 15 MS patients and 15 control subjects within a two-year longitudinal study were used to evaluate cord atrophy with the best method. Statistical evaluation was made by using an intraclass correlation coefficient and Bland-Altman comparisons., Results: Partial-volume modeling with spinal cord inclination correction and partial-volume spinal-cord contour contribution estimation was the most accurate method. The longitudinal test showed a 4% decrease in CCA in MS patients with no significant reduction in control subjects., Conclusion: The automatic PVM cord-segmentation approach, taking into consideration the spinal-cord inclination and partial-volume treatment, provides reproducibility and increased accuracy in the evaluation of cord atrophy, allowing the monitoring of changes in MS patients.

Objective: Quantification of the cerebrospinal fluid (CSF) flow through the aqueduct of Sylvius by means of magnetic resonance imaging (MRI) is subject to interobserver variability due to the region of interest (ROI) selection. Our objective is to develop a semiautomatic measurement method to achieve reproducible quantitative analysis of CSF flow rate and stroke volume., Material and Methods: MR examinations were performed using a 1.5 T scanner with a phase contrast sequence (velocity encoding [V(enc)] of 20 cm/s, FOV = 160, 3 mm slice thickness, image matrix size = 256x256, TR = 53 ms, TE = 11 ms, NSA = 2, flip angle = 15 degrees and 23 frames per cardiac cycle with peripheral retrospective pulse gating). Our method was developed using MATLAB R7. Errors introduced by background offset and possible aliased pixels were automatically detected and corrected if necessary in order to calculate the flow parameters that characterize CSF dynamics. The semiautomatic seed method reproducibility was evaluated and compared with the radius method by two observers analysing 21 healthy subjects., Results: The measurements using the semiautomatic seed method reduced the interobservers variability (intra-class correlation [ICC] = 1.0 for stroke volume and for volumetric flow rate) versus the radius method (ICC = 0.46 for stroke volume and 0.65 for flow rate). Normal stroke volume (39.19 +/- 20.13 microl/cycle), flow rate (3.81 +/- 2.81 ml/min), maximal mean systolic velocity (5.27 +/- 1.3 cm/s) and maximal mean diastolic velocity (4.20 +/- 1.4 cm/s) were calculated with the half moon and aliasing corrected seed method., Conclusions: Semiautomatic measurements (seed method with half moon background and aliasing correction) allow a generalization of the calculus of flow parameters with great consistency and independency of the operator.

Our objective was to analyse the usefulness of single-slice MR-myelography images as a complementary test to conventional MR of the spine in patients with clinically suspected degenerative spine disease. A prospective analysis of 1022 consecutive patients studied with conventional MR and MR-myelography (four acquisitions: one coronal plane, one sagittal plane, and two oblique lateral, right and left planes) examinations was performed. Conventional MR and MR-myelography studies were classified as positive when morphological or structural alterations were noted. Positive MR-myelography information was also categorized as relevant if findings were considered important and radiologically significative to the final diagnosis (either by increasing the radiologists confidence in the diagnosis or because the findings were not observed in the conventional study). Other positive findings were considered non- relevant. There were 62% cases considered positive in the MR-myelography examination. Of them, 3% revealed no alterations on the conventional MR examination. Of the negative MR-myelography studies, 75% had a positive conventional MR examination. Considered as diagnostic techniques, their Kappa concordance was poor. However, MR-myelography complemented the information obtained with the conventional MR examination of the spine, this information being relevant to the final MR diagnosis in 22% of the total number of cases. The contribution of MR-myelography was not different in the three spinal levels. In conclusion, MR-myelography complements the information obtained with conventional MR in a large number of cases., (Copyright 2004 ESMRMB)

Unlabelled: This article presents a pattern-recognition approach to the soft tissue tumors (STT) benign/malignant character diagnosis using magnetic resonance (MR) imaging applied to a large multicenter database., Objective: To develop and test an automatic classifier of STT into benign or malignant by using classical MR imaging findings and epidemiological information., Materials and Methods: A database of 430 patients (62% benign and 38% malignant) from several European multicenter registers. There were 61 different histologies (36 with benign and 25 with malignant nature). Three pattern-recognition methods (artificial neural networks, support vector machine, k-nearest neighbor) were applied to learn the discrimination between benignity and malignancy based on a defined MR imaging findings protocol. After the systems had learned by using training samples (with 302 cases), the clinical decision support system was tested in the diagnosis of 128 new STT cases., Results: An 88-92% efficacy was obtained in a not-viewed set of tumors using the pattern-recognition techniques. The best results were obtained with a back-propagation artificial neural network., Conclusion: Benign vs. malignant STT discrimination is accurate by using pattern-recognition methods based on classical MR image findings. This objective tool will assist radiologists in STT grading.

Rationale and Objectives: To evaluate the prevalence of popliteal cysts in patients studied with magnetic resonance (MR) imaging. Cyst presence and volume will be related to other internal derangement of the knee., Materials and Methods: Three hundred and eighty-two consecutive patients with a MR study of the knee were included. Images were obtained in the three spatial orthogonal planes and evaluated through consensus. Four categories were established for the Baker cyst and synovial fluid (absence, minimum, moderate and massive), and the presence of meniscal, cruciate ligaments and cartilage lesions were recorded. Statistical analysis was carried out with bivariate analysis (chi(2) of Pearson and Gamma tests)., Results: From the 382 patients, 145 had Baker cysts (38.0%). Cyst content was minimum in 99, moderate in 34 and massive in 12. Joint effusion was observed in 269 patients (70.4%), being minimal in 140 patients, moderate in 119 and massive in ten. Meniscal lesions were observed in 195 patients (51%), while 58 patients (15%) had a cruciate ligament lesion. Baker cyst had a statistically significant direct relationship with the presence and quantity of synovial fluid (P=0.002) and with the presence and type of meniscal lesion (P=0.01) but not with cruciate ligaments or cartilage lesions., Conclusions: The prevalence of Baker cysts in MR studies of the knee is high. Its presence and volume are related to the quantity of synovial fluid, and to the presence and severity of meniscal lesions.

Rationale and Objectives: To determine the relationship between the lesion and the scar enhancement characteristic in a series of hepatic Focal Nodular Hyperplasia (FNH) lesions studied with dynamic MR imaging., Methods: Nine patients with FNH were studied. The slice showing the largest scar was selected for the dynamic single slice T1-weighted Gradient-echo sequence before and after contrast administration (15 images, one every 20 s). Analysis was performed with ROI measurements in the lesion and the scar. Signal-intensity and enhancement curves were obtained from both structures., Results: Dynamic MRI showed the typical homogeneous early enhancement of the lesion with delayed enhancement of the scar. The scar enhanced early and vigorously in all cases. Two patterns of enhancement curves were defined. In the parallel pattern, both curves started early, quickly reaching a plateau maintained over time (77.8%). In the divergent pattern the curve of the scar was above the curve of the FNH (22.2%), after the maximum slope was reached, with progressive separation of the curves., Conclusion: There is a hypervascular scar enhancement within FNH lesions with either a parallel or divergent course after the maximum early enhancement.

To determine the relationship and the degree of agreement between radiographs and MR images for the existence of osteoid matrix and periosteal reactions in the initial diagnosis of osteosarcomas, the plain radiographs and MR studies of 54 patients with proven osteosarcoma were retrospectively evaluated. In each tumor the visualization and type of osseous matrix, periosteal reaction and Codman angle were recorded independently for both techniques and by consensus between two radiologists. In 37 tumors agreement existed regarding osteoid matrix and in 31 cases regarding periosteal reactions. The Kappa statistic showed a significant relationship between both tests (0.49 and 0.44, respectively). Both techniques were also not statistically different in the proportion of findings with the McNemar test. Therefore, the ability of MR images seems important in reporting the MR features of bone tumors. Identification of osteoid mineralization and periosteal reaction can also be used with MR in the diagnosis of osteosarcoma.